1. Field of the Invention
The present invention relates to a work train and a method for exchanging old ties for new ties. The train comprises sequentially arranged cars including freight cars for storing old ties and new ties, the train extending in a longitudinal direction and the cars being movable in an operating direction along an existing railroad track comprised of rails fastened to the old ties resting on a ballast bed, the train comprising a tie exchange device for laterally pulling respective ones of the old ties out of the track, and a crane for transporting the old ties pulled out of the track and movable in the longitudinal direction, the crane comprising a tie gripping device.
2. Description of the Prior Art
U.S. Pat. No. 4,809,614 discloses such a work train with a number of work cars and a number of freight cars for storing old and new ties preceding the work cars in the operating direction. The work cars have upwardly recessed machine frames receiving various tie exchange devices which are adjustable with respect to the longitudinal direction on the machine frames so that the ties may be exchanged while the train continuously moves along the track. A guide track atop the freight cars and the work cars extends along the train and supports a gantry crane for transporting old and new ties along the train. With this work train, the entire tie exchange operation, including loosening and removing the old ties, rehabilitating the ballast bed, inserting and fastening the new ties, tamping the ballast, and sweeping the track can be accomplished in a single operation as the work train continuously moves along the track.
The work train disclosed in U.S. Pat. No. 4,878,435 is comprised of two independently moving units, a first one of which carries a tie pulling device for removing the old ties while the second unit carries a similarly structured tie inserting device for the new ties. Each unit is coupled to a freight car for storing the old and new ties, respectively, with a gantry crane for transporting the ties.
U.S. Pat. No. 5,193,461 discloses a tie exchange machine with a tie exchange device which both removes old ties and inserts new ties while the machine stands still. A freight car is coupled to the machine for storing the old and new ties, and a gantry crane for transporting the ties runs between the freight car and a tie storage device arranged on the frame of the machine adjacent the tie exchange device.
Austrian patent No. 389,338 discloses a tie exchange work train with work cars and freight cars for storing ties coupled thereto. Two gantry cranes run on guide tracks extending the length of the train for respectively transporting the removed old ties and the new ties to be inserted. A special motorized crane is provided for unloading the new ties from the deep freight cars.